check out the work of the late professor Dr. John Lorber on the student without a brain who went on to graduate with an honours B.A in Maths at the university of Cambridge.You can read about this case here: Is Your Brain Really Necessary?
Most of current knowledge is simply the 'party line' cross it at your peril.
This case is by no means as rare as it seems. In 1970, a New Yorker died at the age of 35. He had left school with no academic achievements, but had worked at manual jobs such as building janitor, and was a popular figure in his neighbourhood. Tenants of the building where he worked described him as passing the days performing his routine chores, such as tending the boiler, and reading the tabloid newspapers. When an autopsy was performed to determine the cause of his premature death he, too, was found to have practically no brain at all. Professor Lorber has identified several hundred people who have very small cerebral hemispheres but who appear to be normal intelligent individuals. Some of them he describes as having ‘no detectable brain’, yet they have scored up to 120 on IQ tests.This comes from a web-site with a lot of fascinating and strange stuff, Alternative Science.